Artificial food casings used throughout the world in processing a great variety of meat and other food products, such as sausages of various types, cheese rolls, turkey rolls, and the like are customarily prepared from regenerated cellulose and other cellulosic materials. Casings are of several different types and sizes to accommodate different categories of food products to be prepared. They are normally made in long lengths and then shirred and compacted by conventional methods to form a so-called casing stick for use in a stuffing apparatus. The food product, e.g., meat, to be packaged is ordinarily prepared in the form of an emulsion which is stuffed into a deshirred casing on the stuffing apparatus. The food product is processed while it is encased and may be stored and shipped in the casing, though in many instances, particularly with small sausage products, such as frankfurters, the casing is removed from the food product after completion of the processing.
Shirring techniques for food casings are well known in the art. Generally, these techniques involve the continuous feeding of a given length of flat casing feed stock from a reel or other supply into a shirring machine, about a shirring mandrel, where it is inflated with low pressure gas, (e.g. air) and lubricated internally and externally. The inflated and lubricated casing is then passed through an array of shirring rolls which pleat the casing up against a restraint on or about the shirring mandrel until a preselected shirred length has been attained. The shirred casing is then transferred past or away from the restraint against which the shirring was performed and onto an extended mandrel portion whereon it is compacted into a desired stick length.
It has been the goal of food casing manufacturers to produce a casing stick which can be shirred and continuously stuffed on a stuffing apparatus with no mechanical defects or breakdowns so as to insure continuous production. The casing sticks so produced should also have sufficient structural and mechanical integrity to withstand the ordinary rigors of packaging, storage, handling and placement on the stuffing apparatus. It has been furthermore desirable to compact as much stuffable casing into a given stick length as is possible, to produce a shirred casing stick having a high pack ratio with a large internal bore, as evidenced by a high packing efficiency (0.50 and greater).
These goals have been attained to a great extent by recent major developments in the synthetic food casing industry. One such development is disclosed and claimed in the co-pending application Ser. No. 363,851 of Mahoney et al, filed on Apr. 5, 1982, wherein a casing article comprises a central substantially rigid hollow tubular core on which the casing is shirred and compressed. It has been found that significantly higher packing efficiencies are possible with this newly developed cored shirred casing stick article as compared to conventional casing articles of the prior art. Cored casing stick articles are prepared with a wide range of casing sizes, from frankfurter size (15-40 mm diameter) to larger size cellulosic and fiber-reinforced cellulosic casings (40-200 mm).
In the co-pending application Ser. No. 273,180 of Beckman et al, filed on June 12, 1981, there is also disclosed and claimed a further development of this cored high density shirred casing stick concept wherein the core itself is employed as an element of the stuffing system in which the article is incorporated. Specifically, the core of the shirred casing article is employed as a reciprocally movable tension sleeve on a conventional automatic stuffing apparatus. To this end, the rigid hollow tubular core is provided with a means for operably connecting the tension sleeve to a slacking mechanism on the stuffing machine.
In addition to the connection means, the hollow tubular core is further provided with a shoulder element disposed between the end of the compacted casing and the connection means itself. The purpose of the shoulder element is to retain the end of the shirred casing in spaced relationship from the connection means at one end of the tubular core and to facilitate the operable connection of a slacking mechanism on the stuffing apparatus.
Specifically, the means for connecting the tension sleeve to a slacking mechanism may constitute an annular flange formed integrally at one end of the hollow tubular core. The shoulder element for spacing the shirred casing from the connection means may be provided simply by forming a bell or bell shape at the same end of the hollow core. During assembly of a casing article as described above, the shirred casing is forcibly moved along the length of the hollow core until it reaches the shoulder element formed by the bell or bell shape which acts as a stop. In order to obtain a high packing ratio or density, a longitudinal force is applied to the shirred casing in order to compact the casing on the tubular sleeve. This force is transferred to the hollow tubular core which is supported at the same end where the shoulder or bell is formed. Consequently, the shoulder or bell is required to withstand all of the mechanical stress applied to the hollow core during the compaction operation. Since the hollow tubular core is ordinarily made from a relatively thin wall plastic tube having limited capacity to withstand these stresses, the tube sometimes deforms or even ruptures at the shoulder or bell during assembly of the casing articles.
It is therefore an important object of the present invention to provide an improved food casing article of the type wherein a shirred food casing is compacted onto a rigid hollow tubular core member serving as a casing carrier.
Another object of the present invention is to provide such an improved food casing article employing a casing retention element which can be formed quite easily during shaping of the hollow tubular core member with little or no additional expense and which acts at the same time as a reinforcement for the tube against deformation or rupture upon compacting the shirred casing onto the hollow tubular core member.
Another object of the present invention is to provide such an improved food casing article employing a rigid, thin wall, plastic, hollow tubular core member formed with a radially outwardly extending, annular flange which serves as a casing retention element.
Still another object of the present invention is to provide an improved method of forming a radially outwardly extending, annular flange around the side walls of a rigid, thin wall, thermoplastic tube suitable for use as a hollow tubular core in food casing articles.